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 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.security;

/**
 * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
 * for the {@code Policy} class.
 * All the abstract methods in this class must be implemented by each
 * service provider who wishes to supply a Policy implementation.
 *
 * <p> Subclass implementations of this abstract class must provide
 * a public constructor that takes a {@code Policy.Parameters}
 * object as an input parameter.  This constructor also must throw
 * an IllegalArgumentException if it does not understand the
 * {@code Policy.Parameters} input.
 *
 * @since 1.6
 */

public abstract class PolicySpi {

  /**
   * Check whether the policy has granted a Permission to a ProtectionDomain.
   *
   * @param domain the ProtectionDomain to check.
   * @param permission check whether this permission is granted to the specified domain.
   * @return boolean true if the permission is granted to the domain.
   */
  protected abstract boolean engineImplies
  (ProtectionDomain domain, Permission permission);

  /**
   * Refreshes/reloads the policy configuration. The behavior of this method
   * depends on the implementation. For example, calling {@code refresh}
   * on a file-based policy will cause the file to be re-read.
   *
   * <p> The default implementation of this method does nothing.
   * This method should be overridden if a refresh operation is supported
   * by the policy implementation.
   */
  protected void engineRefresh() {
  }

  /**
   * Return a PermissionCollection object containing the set of
   * permissions granted to the specified CodeSource.
   *
   * <p> The default implementation of this method returns
   * Policy.UNSUPPORTED_EMPTY_COLLECTION object.  This method can be
   * overridden if the policy implementation can return a set of
   * permissions granted to a CodeSource.
   *
   * @param codesource the CodeSource to which the returned PermissionCollection has been granted.
   * @return a set of permissions granted to the specified CodeSource. If this operation is
   * supported, the returned set of permissions must be a new mutable instance and it must support
   * heterogeneous Permission types. If this operation is not supported,
   * Policy.UNSUPPORTED_EMPTY_COLLECTION is returned.
   */
  protected PermissionCollection engineGetPermissions
  (CodeSource codesource) {
    return Policy.UNSUPPORTED_EMPTY_COLLECTION;
  }

  /**
   * Return a PermissionCollection object containing the set of
   * permissions granted to the specified ProtectionDomain.
   *
   * <p> The default implementation of this method returns
   * Policy.UNSUPPORTED_EMPTY_COLLECTION object.  This method can be
   * overridden if the policy implementation can return a set of
   * permissions granted to a ProtectionDomain.
   *
   * @param domain the ProtectionDomain to which the returned PermissionCollection has been
   * granted.
   * @return a set of permissions granted to the specified ProtectionDomain. If this operation is
   * supported, the returned set of permissions must be a new mutable instance and it must support
   * heterogeneous Permission types. If this operation is not supported,
   * Policy.UNSUPPORTED_EMPTY_COLLECTION is returned.
   */
  protected PermissionCollection engineGetPermissions
  (ProtectionDomain domain) {
    return Policy.UNSUPPORTED_EMPTY_COLLECTION;
  }
}
